1. Field of the Invention
The present invention relates to a transmission apparatus and method, a recording medium, and a program product, in particular to a transmission apparatus and method, a recording medium, and a program product which allow mitigating packet losses easily and reliably.
2. Description of the Related Art
The Internet has nowadays become popular and it has become practical to distribute a variety of contents through the Internet. There have been a variety of proposals to solve problems in providing contents through the Internet. For example, in the case of downloading music data, it is proposed, in Japanese Laid Open Patent No. 2002-215516, to effectively download the data in accordance with the current use of a buffer for streaming reproduction by requesting the data to be divided into several portions and transferred in several times because of a limited capacity of the buffer.
On the other hand, if distributing a video data, a method is often used in which the video data is packetized into packets corresponding to the RTP (Real Time Transport Protocol) protocol and then transmitted by way of the UDP (User Datagram Protocol) protocol.
However, if the UDP protocol is used and a firewall 3 exists between a transmission apparatus 1 and a reception apparatus 2 as shown in FIG. 1, it is often the case that the firewall 3 is configured so as not to allow a packet corresponding to the UDP protocol to pass through the firewall 3, so that it is not possible to deliver video data through the Internet by way of the RTP/UDP protocols.
If the video data is communicated between the transmission apparatus 1 outside the firewall 3 and the reception apparatus 2 inside the firewall 3, firstly a connection is established between the apparatuses according to the TCP (Transport Control Protocol) protocol. The video data is delivered over the TCP connection. In the firewall 3, it is often the case that an HTTP (Hyper Text Transfer Protocol) proxy server is in operation. Since the HTTP is an upper layer protocol higher than the TCP and the TCP connection can be established thus allowing access by way of the HTTP protocol. As a result the transmission apparatus 1 can transmit the video data to the reception apparatus 2 through the firewall 3.